21052861920 has 216 divisors, whose sum is σ = 73561813416. Its totient is φ = 5482842624.

The previous prime is 21052861891. The next prime is 21052861927. The reversal of 21052861920 is 2916825012.

21052861920 is a `hidden beast` number, since 2 + 10 + 5 + 2 + 8 + 619 + 20 = 666.

It is a super-3 number, since 3×21052861920³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21052861927) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2658607 + ... + 2666513.

It is an arithmetic number, because the mean of its divisors is an integer number (340563951).

Almost surely, 2^21052861920 is an apocalyptic number.

21052861920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21052861920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36780906708).

21052861920 is an abundant number, since it is smaller than the sum of its proper divisors (52508951496).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21052861920 is a wasteful number, since it uses less digits than its factorization.

21052861920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8014 (or 7960 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The spelling of 21052861920 in words is "twenty-one billion, fifty-two million, eight hundred sixty-one thousand, nine hundred twenty".